Energy

• Thermal energy store


  A store of energy in the form of heat e.g. hot coffee and a turned-on radiator
• Gravitational potential energy store

  A store of energy due to an object's position in a gravitational field e.g. skydiver and a crate being lifted up
• Chemical energy store


  A store of energy in the bonds between atoms in a chemical substance e.g. batteries and fuel
• Kinetic energy store


  A store of energy due to an object's motion e.g. car and runner in motion
• Gravitational potential energy of a sky diver


  Decreases as they fall
• Kinetic energy of a sky diver

  Increases as they fall
• Kinetic energy of a car

  Decreases when it brakes, and the energy is transferred to the brakes (as heat)
• Law of conservation of energy


  Energy cannot be created or destroyed, it can only be transformed from one form to another
• Dissipate


  To spread or scatter energy in such a way that it becomes less concentrated or less able to be usefully applied
• Doing work


  Applying a force to an object and causing it to move in the direction of the force e.g. pushing a box in a straight line
• Moment


  The turning effect of a force about a pivot or axis
• Energy is the ability to do work
• Work done = force x distance moved by object
• The energy transferred from one place to another is called power
• Power = rate at which energy is transferred
• Smart Triangle for work, force and distance

  
• Pivot


  The fixed point around which a lever rotates
• Effort


  The force applied to a lever
• Load


  The force that needs to be moved by the lever
• Calculating the moment of a seesaw

  1. Force = 500N

  2. Distance from pivot = 1.5 metres
• Conduction


  The transfer of heat through a material without the involvement of any bulk motion of the material
• List two states of matter that allow conduction

  • solid
  • liquid
• Conduction occurs more quickly in metals compared to non-metals
• Convection


  The transfer of heat by the movement of a fluid such as air or water
• Infrared radiation is measured in micrometres
• Surfaces that best absorb infrared radiation:

  Black and matted
• Surfaces that best reflect infrared radiation:

  White and shiny
• Temperature


  A measure of the average kinetic energy of the particles in a substance
• Internal energy


  The total kinetic and potential energy of all the particles in a substance